Proportional solenoid-controlled fluid valve having compact pressure-balancing armature-poppet assembly

ABSTRACT

A proportional solenoid-driven valve control assembly contains a moveable, magnetic armature adjacent to a fixed pole piece, providing fluid leakage containment, and having no non-magnetic element for alignment, support or magnetic flux path control. A valve unit coupled with the armature contains a fluid cavity in fluid communication with a fluid inlet port and a fluid exit port. The valve is closed by a poppet coupled with the armature. To compensate for fluid pressures exerted against the poppet, a flow restriction is provided between an armature cavity and the fluid cavity. Also, a bore is formed through the armature to provide fluid communication between the fluid exit port and the armature cavity. This serves to balance fluid pressures at the fluid inlet and exit ports applied to the opposite sides of the fluid flow restriction.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application is a continuation-in-part of co-pendingU.S. patent application Ser. No. ______, filed ______, by V. Kumar,entitled: “Proportional Solenoid-Controlled Fluid Valve Assembly WithoutNon-Magnetic Alignment Support Element” (hereinafter referred to as the'______ application), which is a continuation-in-part of co-pending U.S.patent application Ser. No. 09/846,425, filed May 1, 2001, by V. Kumar,(hereinafter referred to as the '425 application), which is acontinuation of U.S. patent application Ser. No. 09/535,757, filed Mar.28, 2000, now U.S. Pat. No. 6,224,033, issued May 1, 2001 (hereinafterreferred to as the '033 Patent), which is a continuation of U.S. patentapplication Ser. No. 08/988,369, filed Dec. 10, 1997, now U.S. Pat. No.6,047,947 (hereinafter referred to as the '947 Patent), issued Apr. 11,2000, which is a continuation-in-part of U.S. patent application Ser.No. 08/632,137, filed Apr. 16, 1996, now U.S. Pat. No. 5,785,298, issuedJul. 28, 1998 (hereinafter referred to as the '298 Patent), eachapplication being assigned to the assignee of the present applicationand the disclosures of which are incorporated herein.

FIELD OF THE INVENTION

[0002] The present invention relates in general to solenoid-actuatedfluid control valves of the type disclosed in the above-referencedapplications and Patents, for use in precision fluid flow regulationsystems, such as those that require precise control of the rate of fluidflow, including but not limited to pneumatic and hydraulic regulation.The present invention is particularly directed to a reduced hardwarecomplexity configuration for effectively balancing inlet and outletpressures of the fluid ports of the valve, so that valve poppet positionwill be defined exclusively by the solenoid, thereby ensuring precisioncontrol of fluid flow through the valve.

BACKGROUND OF THE INVENTION

[0003] A number of precision fluid metering applications, such asmicro-pneumatic and fuel injection systems, as non-limiting examples,employ solenoid-driven actuators to control fluid flow through a fluidsupply valve. Optimally, fluid flow through the valve is to bemaintained very closely proportional to the current applied to thesolenoid. However, varying fluid pressure conditions at the valve'sinlet and/or outlet ports can significantly impact the ability of thesolenoid to provide the precise metering control desired.

[0004] In order to deal with this problem, it is common practice toincorporate into the valve a pressure balancing sub-assembly, such as adual diaphragm-based pressure-balancing mechanism of the typediagrammatically shown in cross-section in FIG. 1. This dual diaphragmmechanism serves to compensate or effectively ‘balance’ out the fluidpressures at each of its inlet and outlet ports, in order that the onlytranslation forces acting on the valve orifice-closing poppet will bethose imparted by the solenoid-driven armature.

[0005] More particularly, in the valve architecture of FIG. 1,compensation for the pressure P1 of a fluid applied to a valve inletport 11 of a solenoid-operated fluid valve 10 is provided by an ‘upper’diaphragm 21, installed between an armature-poppet connecting rod 23 anda solenoid actuator assembly 25. The upper end of the connecting rod 23engages the moveable armature 24 of the solenoid actuator, while thelower of the connecting rod 23 engages a poppet 27, that is sized to beclosed against a valve seat 31 surrounding a valve orifice 33. The valveorifice 33 provides fluid communication between a fluid cavity 35, towhich fluid inlet pressure P1 at the valve inlet port 11 is applied, anda fluid exit port 37 from which fluid at a valve outlet pressure P2 isderived.

[0006] By making the annular area A_(D1) of the ‘upper’ diaphragm 21substantially the same as or very close to that of the area A_(O) of theorifice 33, the downward force (as viewed in FIG. 1) imparted by theinlet fluid pressure P1 against the poppet 27 will be substantially thesame as or performance-wise sufficiently close to the ‘upward’ forceimparted by the pressure P1 against the upper diaphragm 21, therebyeffectively neutralizing the contribution of the pressure P1 to theposition of the valve poppet 27 relative to the valve seat 31.

[0007] In a complementary manner, compensation for the fluid pressure P2at the exit port 37 is provided by a ‘lower’ diaphragm 41, installedbetween the lower end 43 of a poppet-connecting rod 45 and the valvebody 47. The upper end 51 of the connecting rod 45 engages the poppet27. Similar to the compensation mechanism for the pressure P1, theannular area A_(D2) of the ‘lower’ diaphragm 41 is made substantiallythe same as or very close to that of the area A_(O) of the orifice 33.

[0008] As a consequence, any upward force imparted by the pressure P2against the poppet 27, that might otherwise tend to lift the poppet offthe valve seat 31 (and thereby undesirably render solenoid controlineffective), will be countered by ‘downward’ force imparted by thepressure P2 against the lower diaphragm 41, so as to effectivelyneutralize the contribution of the pressure P2 to the position of thevalve poppet 27 relative to valve seat 31.

[0009] Now, although a dual diaphragm-based pressure compensationstructure of the type shown in FIG. 1 is effective for its intendedpurpose, it is hardware intensive in terms of the added diaphragm,connecting rods and increased sized and additional boring of the valvebody proper. This added hardware complexity not only increases the sizeof the assembly, but the cost and complexity of its manufacture, aswell.

SUMMARY OF THE INVENTION

[0010] In accordance with the present invention, advantage is taken ofthe magnetic field coupling and fluid containment structure of theintegrated ferromagnetic pole piece employed in the solenoid-operatedvalve described in the above-referenced '______ application, toincorporate a poppet/armature bore-based, pressure-balancing scheme,that not only ensures that valve poppet position will be definedexclusively by the solenoid, but does so in a manner that allows thehardware complexity, size and cost of assembly to be significantlyreduced relative to the prior art, such as the dual diaphragm structure,described above.

[0011] As will be described, the pressure balanced, solenoid-controlledfluid valve assembly of the invention includes a valve unit and asolenoid-driven, valve actuator. The solenoid-driven, valve actuatorunit is preferably of the type described in my above-referenced '______application, having an integrated magnetic pole piece that providesfluid leakage containment. It also couples axial, radial and magneticshunt flux paths with a moveable armature without the need fornon-magnetic material for alignment, support or magnetic flux flow pathcontrol. The valve unit is similar to the those of the above-referenced'425 application, and the '947 and '033 Patents, positioning a valvepoppet relative to a fluid flow orifice through the valve proper.

[0012] To balance out inlet and exit port fluid pressures, the valveunit incorporates a fluid flow restriction with thearmature/poppet-positioning mechanism between the armature cavity andthe fluid inlet cavity. In addition, the poppet and itspoppet-positioning armature have an interior bore that serves as anauxiliary fluid path between the fluid exit port and the armaturecavity. This combination is effective to balance fluid pressures at thefluid inlet and exit ports applied to the opposite sides of therestriction, in a manner that is complementary to the fluid pressuresapplied to opposite sides of the poppet, thereby effectivelyneutralizing the effects of fluid pressure on poppet position.

[0013] In a first embodiment, a poppet/armature assembly is coupled witha pressure-balancing diaphragm, that has an annular area substantiallythe same as or very close to the area of the valve bore orifice. Thediaphragm is retained by an armature support member, so as to provide afluid seal between an upper armature cavity containing the armature, anda cavity containing the valve seat, and ported to the fluid inlet port.

[0014] The valve actuator unit includes a unitary pole piece having agenerally axial pole piece portion, that extends into an uppersolenoid/pole piece cavity coupled in fluid communication with the upperarmature cavity by way of an annular fluid gap. Fluid leakagecontainment for this upper cavity structure is provided by thefluid-sealing structure of the pole piece and the diaphragm. Theintegral pole piece and support architecture do not require anon-magnetic material in the magnetic flux flow path. An axial bore inthe lower end of the axial portion of the pole piece accommodates acompression spring urged against the armature and axially biases thearmature, and thereby the poppet against the valve seat.

[0015] An auxiliary axial bore through the armature provides fluidcommunication between the valve bore, (which is in fluid communicationwith the fluid exit port, and the axial gap between the lower distal endof the axial portion of the magnetic pole piece. Since the axial gap isin fluid communication with the upper (fluid leakage-contained) cavitystructure that includes the upper solenoid/pole piece cavity and thearmature cavity, it couples the exit port pressure to the top side ofthe fluid restriction diaphragm.

[0016] Since, the area of the fluid restriction diaphragm issubstantially the same as the valve bore orifice upward force impartedagainst the poppet by the fluid exit port pressure is countered by adownward force at that same pressure, that has coupled through theauxiliary bore to the top of the diaphragm. In a complementary manner,the pressure at the fluid inlet port is balanced as a result of adownward force imparted by the inlet fluid pressure against the poppetbeing substantially the same as the upward force imparted by thepressure against the bottom of the fluid restriction diaphragm.

[0017] In a second embodiment, the fluid restriction comprises an O-ringinserted into an annular groove of an armature support member. Similarto the diaphragm of the first embodiment, this O-ring has an annulararea substantially the same as or very close to that of the area of thevalve bore orifice. A single spiral-configured suspension springsupports the armature-poppet. The pressure-balancing function providedby the O-ring is similar to that of the diaphragm in the firstembodiment.

[0018] Pursuant to a third embodiment, the fluid restriction mechanismis implemented without a captured element; instead, the restriction isdefined by the geometry of a very narrow annular aperture between theouter surface of the armature-poppet and the inner surface of anarmature insertion bore through the surrounding support member. Thegeometric parameters of the armature-poppet, including its outerdiameter and auxiliary internal bore size, and those of the armatureinsertion bore through the support member, are such as to limit orrestrict ‘upward’ fluid flow of the inlet pressure and ‘downward’ fluidflow of the outlet pressure, in a manner that is proximate the forceimparted by these pressures on opposite sides of the armature-poppetrelative to the valve orifice. This neutralizes the contribution of thefluid inlet and outlet pressures on the position of the armature-poppetrelative to the valve seat.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a longitudinal, cross-sectional diagrammaticillustration of a proportional solenoid-controlled fluid valve assemblycontaining a conventional dual diaphragm-based fluid pressurecompensation mechanism;

[0020]FIG. 2 is a longitudinal, cross-sectional diagrammaticillustration of a first embodiment of the improved proportionalsolenoid-controlled fluid valve assembly embodying the fluid pressurecompensation scheme of the invention;

[0021]FIG. 3 diagrammatically illustrates a second embodiment of theinvention, in which the fluid restriction mechanism is implemented bymeans of an O-ring inserted into an annular groove of an armaturesupport member; and

[0022]FIG. 4 diagrammatically shows a third embodiment of the invention,in which the fluid restriction mechanism is implemented by a narrowannular aperture between the outer surface of the armature-poppet andthe inner surface of an armature insertion bore in the armature supportmember.

DETAILED DESCRIPTION

[0023] Attention is now directed to FIG. 2, which is a longitudinal,cross-sectional diagrammatic illustration of a proportionalsolenoid-controlled fluid valve, having a fluid pressure balancingarrangement in accordance with a first embodiment of the invention.Unless otherwise indicated or inherently apparent, the architecture ofFIG. 2 (as well as those of FIGS. 3 and 4) is cylindrically symmetricalabout a longitudinal axis A.

[0024] As pointed out briefly above, and as will be detailed below, thisarrangement employs a fluid flow restriction between the armature cavityand the fluid inlet cavity, plus a fluid communication path through thevalve closing assembly between the fluid exit port and the armaturecavity. The combination of these two mechanisms effectively balancesboth the inlet and outlet forces acting upon the valve poppet, so thatvalve poppet position is controlled exclusively by the solenoid.

[0025] The solenoid-controlled fluid valve assembly includes a valveunit 200 the fluid flow path through which is controlled by asolenoid-driven, valve actuator unit 300. The solenoid-driven, valveactuator unit 300 is preferably of the type described in myabove-referenced '______ application, and employs an integrated magneticpole piece that is configured to provide fluid leakage containment, aswell as axial, radial and magnetic shunt flux paths with a moveablearmature that drives the valve poppet, but without the conventional needfor non-magnetic material for alignment, support or magnetic flux flowpath control.

[0026] The valve unit 200 is similar to the valve units of thesolenoid-controlled valve assemblies of the above-referenced '425application, and the '947 and '033 Patents, and is operative, undersolenoid-driven actuator control, to position a valve poppet relative toa fluid flow orifice through the valve proper. To balance out inlet andexit port fluid pressures, valve unit 200 incorporates a fluid flowrestriction coupled to the armature/poppet-positioning mechanism betweenthe armature cavity and the fluid inlet cavity. In addition, the poppetand its associated poppet-positioning armature are provided within aninterior bore that provides a fluid communication path between the fluidexit port and the armature cavity.

[0027] As pointed out above, and as will be detailed below, thiscombination of the fluid flow restriction and the fluid communicationpath causes fluid pressures at the fluid inlet and exit ports to beapplied to the opposite sides of the restriction, in a manner that iscomplementary to the fluid pressures applied to opposite sides of thepoppet, thereby effectively neutralizing the effects of fluid pressureon poppet position.

[0028] More particularly, the valve unit 200 is shown as comprising agenerally cylindrical base member 202 having a fluid input port 204 anda fluid exit port 206. Each of the fluid input and exit ports, which maybe respectively interiorly threaded, as shown at 208 and 210,respectively, so as to facilitate their being coupled to respectivesections of fluid transporting conduit (not shown). Within the generallycylindrical valve base member 202, the fluid exit port 206 is coupled toa first generally cylindrical interior valve bore 212 that extends to avalve orifice 214, that terminates at and is surrounded by a (generallycircular) valve seat 216.

[0029] Although the valve seat 216 is shown as being fixed within thebody 202 of valve unit 200, it may alternatively be configured as anadjustable valve seat, such as one installed in a threaded portion ofthe valve bore (as shown diagrammatically in the embodiments of FIGS. 3and 4, to be described). In this alternative configuration, the valveseat may be maintained in a fluid sealed condition within the valve bore212 by means of one or more (e.g., a pair of) O-rings. The orifice 214of the valve bore 212 opens into an interior valve poppet cavity 218 inwhich a valve poppet 220 is retained by an translatable, axially boredarmature 222 for solenoid-controlled closure against and opening awayfrom the valve seat 216. The valve poppet cavity 222 is coupled to thefluid inlet port 204 by way of a bore 224 therebetween.

[0030] As further shown in FIG. 2, valve poppet 220 may have a generallystepped cylindrical body 226, which terminates at a lower generallycircular face 228. The poppet face 228 has a depression 230, into whicha fluid tight sealing ring 232, such as an annular shaped neoprene ring,may be press fit. This annular sealing ring 232 is sized to cover andthereby seal the poppet 220 against the circular valve seat 216, whenbrought into closing contact thereagainst by the solenoid-drivenarmature 222.

[0031] The valve poppet 220 also includes an interior axial bore 234,which is sized to snugly engage and fit upon the outer cylindricalsurface 236 of a lower narrow cylindrical end 238 of the axially boredarmature 222. When the valve poppet 220 is affixed upon the lowercylindrical end 238 of the armature 222, it retains an interior ringportion 240 of a diaphragm 242 against the lower surface 244 of thearmature 222. Like the upper diaphragm 21 in the dual diaphragmstructure of FIG. 1, the diaphragm 242 has an annular area A₂₄₂ that issubstantially the same as or very close to that of the area A₂₁₄ of thebore orifice 214.

[0032] A relatively increased thickness, generally circularcircumferential portion 246 of the diaphragm 242 is captured and sealedbetween an interiorly projecting radial portion 248 of an inverted,generally cup-shaped armature support member 250, and a retaining ring252 that is fit (e.g., threaded) into a generally circular depression254 of the support member 250. When so captured, the diaphragm 242provides a fluid seal between an upper armature cavity 256 containingthe armature 222 and the valve poppet cavity 218 containing the poppet220 and the valve seat 216.

[0033] The axially translatable armature 222 has a generally annularshoulder 260 that is adapted to cooperate with an associated surface 262of the support member 250, so as to support a first spiral-configuredsuspension spring 264 on a first side of an inner spring-retaining,ferrule-shaped spacer 266, that is sized to fit around the outercylindrical surface 268 of the armature 222.

[0034] A second spiral-configured suspension spring 270 is capturedbetween a second side of the inner ferrule-shaped spacer 266 and agenerally cylindrically shaped armature sleeve 272, that is retainedupon an upper portion 274 of the armature 222. A generally outercircumferential region 276 of the second spiral suspension spring 270 iscaptured between a generally disc-shaped support member 278 atop thesupport member 250 and an interior surface portion 302 of a lower,cup-shaped portion 304 of a ferromagnetic pole piece 306 ofsolenoid-driven, valve actuator unit 300.

[0035] As pointed out briefly above, and as will be described, thesolenoid-driven, the valve actuator unit 300 is preferably configuredessentially as shown and detailed in the above-referenced '______application. The cup-shaped portion 304 of the pole piece 306 maythreadingly engage the outer cylindrical surface 280 of support member250, with an O-ring 282 providing a fluid seal therebetween. The valvebody 202 is sized to receive and engage a lower interior cylindricalportion 308 of the cup-shaped portion 304 of the pole piece 306.

[0036] The solenoid-driven, valve actuator unit 300 may be securelyattached to the valve unit 200 by way of set-screws (not shown) insertedthrough bores (two of which are shown at 310 and 312) in the pole piece306, and screwed into tapped bores (not shown) in the upper surface 203of the valve body 202. An O-ring 284 is captured between a generallycircular slot 286 of the lower surface 288 of the support member 250 andthe valve body 202, so as to seal the support member 250 against valvebody 202, and thereby provide a sealed or contained fluid flow pathbetween the fluid inlet and exit ports and the poppet cavity 218.

[0037] The axially translatable armature 222 and associated armaturesleeve 274 extend through a generally cylindrical annular bore 314formed by a radially inward projecting portion 316 of magnetic polepiece 306 (that is solid with the cup-shaped portion 304 thereof). As aresult, an outer cylindrical surface 290 of armature sleeve 274 isslightly radially spaced apart from the interior cylindrical surface 318of radially inward projection 316 of the pole piece and forms a narrowannular fluid (air) gap 320 therebetween.

[0038] The generally cylindrical annular bore 314 opens into a uppersolenoid/pole piece cavity 341, that is bounded by a relatively thinportion 342 of a generally annular sleeve pole piece portion 340 of themagnetic pole piece 306. This upper cavity 341 is coupled in fluidcommunication with the upper armature cavity 256 by way of the annularair gap 320. As will be described, fluid leakage containment for thisupper cavity structure is provided by the fluid-sealing integratedstructure of the pole piece 306, on the one hand, and the diaphragm 242,on the other hand. (As noted earlier, the diaphragm 242 provides a fluidseal between an upper armature cavity 256 containing armature 222 andthe valve poppet cavity 218, in which the poppet 220 and the valve seat216 are disposed.)

[0039] Because the annular air gap 320 is very narrow and of a fixedradial distance, the magnetic flux path between the armature 222 and theradially inward projecting portion 316 of the magnetic pole piece 306 isa low magnetic reluctance radial path. Thus, as in the patentedarchitectures, referenced above, the substantial reluctance of the axialair gap 336 between the moveable armature 222 and the distal end of thegenerally axial portion 322 of the magnetic pole piece, in combinationwith the relatively low magnetic reluctance in the radial directionacross the radial air gaps, effectively by-passes the axial air gap andconfines the magnetic flux in radial air gap regions.

[0040] The armature 222 terminates at a generally planar, circular topsurface 294 adjacent to a generally axial or longitudinal portion 322 ofthe magnetic pole piece 306. The generally axial portion 322 of themagnetic pole piece 306 is configured of a generally cylindrical solidferromagnetic element, that is generally coaxial with the axis A and issized to fit within the generally cylindrical bore 324 of a solenoidcoil 326. As shown, the solenoid coil may be installed within a housing328 of ferromagnetic material. The housing 328 may be provided with asidewall aperture or bore 329 for electrical leads 332 that supplyelectrical connection between the solenoid coil and a current controlsource (not shown).

[0041] The generally axial portion 322 of the magnetic pole piece 306has a lower distal end 334 that is axially spaced apart from andmagnetically coupled with the top generally circular surface 294 ofaxially translatable armature 222, so as to form an axial air gap 335therebetween. An axial bore 323 formed in the lower end of the axialportion 322 of the pole piece 306 receives a compression spring 325 thatis urged against the top surface 294 of the axially translatablearmature 222, and serves to axially bias the armature 222 and itsassociated poppet 220 downwardly so that the poppet is urged against thevalve seat 216.

[0042] Extending axially outwardly from the distal end 334 of thegenerally axial portion 322 of the magnetic pole piece 306 is agenerally tubular or ferrule-shaped projection 336, having a tapered orvarying thickness in the axial direction. This tapered ferrule-shapedprojection 336 is radially spaced apart from and magnetically coupledwith outer cylindrical surface 290 of the armature sleeve 274 of thearmature 222, by a radial air gap 338 therebetween, so as to form amagnetic flux path shunt.

[0043] Alternatively, in lieu of providing the annular shunt projection336 on the distal end of the generally axial portion 322 of magneticpole piece 306, an equivalent shunt structure may be provided byconfiguring the top generally circular surface circular surface 294 ofthe armature 222 with a tapered annular projection, that is spaced apartfrom and magnetically coupled with the distal end 334 of the generallyaxial portion 322 of the magnetic pole piece 306. In either case, theferrule-shaped projection allows for relative axial translation betweenthe movable armature 222 and the magnetic pole piece 306, as themoveable armature 222 is axially translated.

[0044] The magnetic pole piece 306 further includes generally annularsleeve pole piece portion 340 that is continuous with the first,generally axial portion 322 and includes relatively thin portion 342that is radially spaced apart from the lower end of the pole pieceportion 322, and becomes rapidly saturated by the magnetic fieldgenerated by the solenoid coil 326. To provide for fluid leakagecontainment, the annular sleeve pole piece portion 340 is madeeffectively mechanically solid with the main pole piece portion 322.

[0045] In the embodiment of FIG. 2, this is accomplished by configuringthe first, generally axial portion 322 of the pole piece 306 as agenerally cylindrical component and externally threaded as shown at 344,so that it may be threaded into a threaded interior cylindrical bore 346of the annular sleeve portion 340 of the pole piece 306. A fluid seal isprovided by means of an O-ring 348 captured within an annular groove 350formed within the cylindrical sidewall of axial pole piece portion 322.In an alternative configuration, the main and annular pole pieceportions may be formed of the same magnetic pole piece element, so as toobviate the need for an O-ring.

[0046] The relatively thin segment 342 of the annular pole piece portion340 extends to and is solid with the radially inward projecting portion316 of the pole piece 306. For mechanical alignment, the cylindricalshape of the radial air gap 320 constrains movement of the armature 222in the axial direction only. This serves to prevent potential off-axisdistortion of the suspension springs 264 and 270, so that properoperation of the valve is not impaired. Axial alignment is reinforced bythe fact that the radial air gap 320 is radially aligned with andaxially offset from the shunt radial air gap 338, thereby providing apair of axially displaced coaxial guide air-bushings that preventoff-axis play between the moveable armature 222 and the fixed magneticpole piece 306.

[0047] However, as described in the '______ application, unlikeconventional solenoid structures, the integral pole piece and supportarchitecture does not require a non-magnetic material in the magneticflux flow path. This reduces manufacturing and hardware complexity andcost associated with solenoid structures having non-ferromagneticmaterials as part of flux path containment and pole piece—armaturealignment.

[0048] As pointed out briefly above, the fluid pressure balancingmechanism of the invention takes advantage of this fluid leakagecontainment functionality of the integrated magnetic pole piece 306, byincorporating an additional fluid flow restriction mechanism between thearmature cavity 256 and the fluid inlet cavity 218, and providing anauxiliary fluid communication path between the armature cavity 256 andfluid exit port 206. In order to realize a compact structure, thisauxiliary communication path is readily implemented without the need forany additional components, such as the connecting rod and additionaldiaphragm components employed in the assembly of FIG. 1, describedabove.

[0049] Instead, as shown in FIG. 2, an auxiliary axial bore 223 isformed through the armature 222, so as to provide fluid communicationbetween the valve bore 212 (which is in fluid communication with thefluid exit port 206) and the axial air gap 335 between the lower distalend 334 of the axial portion 322 of the magnetic pole piece 306. Sincethe axial air gap 335 is in fluid communication with the upper (fluidleakage-contained) cavity structure that includes the cavity 341 andarmature cavity 256, it couples the pressure P2 supplied via theauxiliary bore 223 from the fluid exit port 206 to the top side of fluidrestriction (diaphragm) 242.

[0050] As described above, the fluid restricting diaphragm 242 has anannular area A₂₄₂ that is substantially the same as or very close tothat of the area A₂₁₄ of the orifice 214 of bore 212. As a result, anyupward force imparted by the pressure P2 at the fluid exit port 206against the bottom face 228 of the poppet 220 will be countered by‘downward’ force imparted by the pressure P2, that has coupled throughthe auxiliary bore to the top of the diaphragm 242. This serves toeffectively neutralize the contribution of the pressure P2 to theposition of the valve poppet 220 relative to valve seat 216.

[0051] In a complementary fashion, the pressure P1 at the fluid inletport 204 is balanced as a result of a downward force (as viewed in FIG.2) imparted by the inlet fluid pressure P1 against the poppet 220 beingsubstantially the same as the ‘upward’ force imparted by the pressure P1against the bottom of diaphragm 242.

[0052]FIG. 3 diagrammatically illustrates a second embodiment of theinvention, in which the fluid restriction mechanism is implemented bymeans of an O-ring 360 inserted into an annular groove 362 of anarmature support member 364. Similar to the diaphragm 242 of theembodiment of FIG. 2, O-ring 360 has an annular area A₃₆₀ that issubstantially the same as or very close to that of the area A₃₇₁ of anorifice 371 of a valve bore 370.

[0053] In this embodiment, and also that of FIG. 4, to be described, thearmature/poppet assembly is shown as being configured as a singleintegrated armature/poppet element 366. This armature/poppet element 366contains an auxiliary axial bore 368, that provides fluid communicationbetween valve bore 370 and the axial air gap 335 between the lowerdistal end 334 of the axial portion 322 of the magnetic pole piece 306.

[0054] Moreover, as described above, in the embodiments of FIG. 3 andFIG. 4, a valve seat 376 is shown as having the above-describedalternative adjustable configuration, being installed in a threadedportion 372 of a valve seat installation bore 374 in the valve body. Thevalve seat 376 is maintained in a fluid sealed condition within thevalve installation bore 374 by a pair of O-rings 378 and 380.

[0055] Also, a single spiral-configured suspension spring 382 is used tosupport the armature-poppet element 366. In the embodiment of FIG. 3,the suspension spring 382 is held against an armature sleeve 384 by aretention washer 386. A generally outer circumferential region 388 ofsuspension spring 382 is captured between support member 364 and aninterior ledge surface portion 390 of the cup-shaped portion 304 of theferromagnetic pole piece 306.

[0056] The pressure-balancing function provided by the O-ring 360 in theembodiment of FIG. 3 is similar to that of the diaphragm 242 in theembodiment of FIG. 2, in that an upward force imparted by the pressureP2 at the fluid exit port against the bottom of the armature-poppet 366will be countered by ‘downward’ force imparted by the pressure P2, thathas coupled through the auxiliary bore 368 to the top of the O-ring 360.Also, the pressure P1 at the fluid inlet port 204 is balanced as aresult of a downward force imparted by the inlet fluid pressure P1against armature-poppet 366 being substantially the same as the ‘upward’force imparted by the pressure P1 against the bottom of the O-ring 360.

[0057]FIG. 4 diagrammatically illustrates a third embodiment of theinvention, in which the fluid restriction mechanism is implementedwithout a captured element, such as the diaphragm 242 in the embodimentof FIG. 2 or the O-ring 360 in the embodiment of FIG. 3. Instead, therestriction is defined by the geometry of a very narrow annular aperture400, that is formed between the outer cylindrical surface 402 of thearmature-poppet 366 and the inner cylindrical surface 404 of an armatureinsertion bore 405 through the surrounding support member 364.

[0058] In this embodiment, the geometric parameters of thearmature-poppet 366 (including its outer diameter and auxiliary internalbore size), and those of the armature insertion bore 405 through thesupport member 364, are defined such as to limit or restrict ‘upward’fluid flow therethrough of the inlet pressure P1 and ‘downward’ fluidflow therethrough of the outlet pressure P2, in a manner that isproximate the force imparted by these pressures on opposite sides of thearmature-poppet 366 relative to the valve orifice 371. Again, the netresult is to neutralize the contribution of each of the fluid inlet andoutlet pressures P1 and P2 on the position of the armature-poppetrelative to the valve seat.

[0059] As will be appreciated from the foregoing description, thesolenoid-actuated valve assembly of the invention not only effectivelybalances inlet and outlet pressures of the fluid ports of the valve, butis implemented with reduced hardware complexity. The incorporation of afluid flow restriction between the armature cavity and the fluid inletcavity, plus a fluid communication path through the valve closingassembly, provides a highly integrated structure that reduces overallsize and cost of assembly.

[0060] While I have shown and described several embodiments inaccordance with the present invention, it is to be understood that thesame is not limited thereto but is susceptible to numerous changes andmodifications as known to a person skilled in the art, and I thereforedo not wish to be limited to the details shown and described herein butintend to cover all such changes and modifications as are obvious to oneof ordinary skill in the art.

What is claimed:
 1. A solenoid-actuated valve assembly comprising: asolenoid coil adapted to generate a magnetic field, and having alongitudinal axis and a bore coaxial therewith; an axially movablearmature of magnetic material, supported within an armature cavity foraxial translation along said longitudinal axis; a magnetic pole piecedisposed within the bore of said solenoid coil and being magneticallycoupled with said axially movable armature; a valve unit, mechanicallycoupled with said axially movable armature, and having a fluid cavitycoupled in fluid communication with a fluid inlet port to which fluid isapplied at a first fluid pressure, and a fluid exit port from which saidfluid is output at a second fluid pressure, and containing a valve seattherebetween, which is adapted to be closed by a valve closing assemblythat includes a valve poppet coupled with said moveable magneticarmature, so as to regulate fluid flow between said fluid inlet port andsaid fluid exit ports; and a fluid pressure balancing arrangementadapted to compensate for said first and second fluid pressures beingexerted against said valve poppet, and comprising a fluid flowrestriction between said armature cavity and said fluid cavity, and afluid communication path through said valve closing assembly andproviding fluid communication between said fluid exit port and saidarmature cavity.
 2. The solenoid-actuated valve assembly according toclaim 1, wherein said fluid flow restriction comprises a generallyannular-shaped passageway adjacent to said valve closing assembly andextending between said armature cavity and said fluid cavity.
 3. Thesolenoid-actuated valve assembly according to claim 1, wherein saidfluid flow restriction comprises a fluid seal element, coupled betweensaid valve closing assembly and said valve unit in a manner thatprevents fluid communication between said inlet port and said armaturecavity.
 4. The solenoid-actuated valve assembly according to claim 3,wherein said fluid seal element comprises a diaphragm.
 5. Thesolenoid-actuated valve assembly according to claim 3, wherein saidfluid seal element comprises an O-ring.
 6. The solenoid-actuated valveassembly according to claim 1, wherein said magnetic pole piece includesa first, generally axial portion having an end thereof axially spacedapart from and magnetically coupled with said axially movable armature,a second, generally annular portion continuous with said first,generally axial portion of said magnetic pole piece and being spacedapart from said end thereof, and a third, generally radial portioncontinuous with said second, generally annular portion, and beingmagnetically coupled with said axially moveable armature.
 7. Thesolenoid-actuated valve assembly according to claim 6, wherein saidthird, generally radial portion of said magnetic pole piece is solidwith a housing for said solenoid coil, so that support for and axialalignment of first portion of said magnetic pole piece relative to saidaxially moveable armature is provided by said second and third portionsof said magnetic pole piece continuous therewith, and is exclusive of anon-magnetic element.
 8. The solenoid-actuated valve assembly accordingto claim 7, wherein said second and third portions of said magnetic polepiece are configured to form, with said housing, a generally annularspace that receives a portion of said solenoid coil.
 9. Thesolenoid-actuated valve assembly according to claim 6, wherein saidthird portion of said magnetic pole piece includes a radially inwardlyprojecting portion that is adjacent to but radially spaced apart fromand magnetically coupled with said axially moveable armature.
 10. Thesolenoid-actuated valve assembly according to claim 6, wherein saidthird, generally radial portion of said magnetic pole piece is attachedto said valve unit.
 11. The solenoid-actuated valve assembly accordingto claim 6, wherein said first and second portions of said magnetic polepiece are configured to be relatively axially adjustable.
 12. Thesolenoid-actuated valve assembly according to claim 6, wherein saidsecond and third portions of said magnetic pole piece are separateportions of the same pole piece element.
 13. The solenoid-actuated valveassembly according to claim 11, wherein said first and second portionsof said magnetic pole piece are provided with a fluid seal therebetween.14. The solenoid-actuated valve assembly according to claim 6, whereinsaid magnetic pole piece is configured to form a magnetic flux shuntpath with said axially moveable armature.
 15. The solenoid-actuatedvalve assembly according to claim 1, wherein said axially moveablearmature is spring-supported outside said bore for axial translationrelative to said magnetic pole piece.
 16. A solenoid-actuated valveassembly comprising a a solenoid coil having a longitudinal axis and asolenoid cavity coaxial therewith, said solenoid coil producing amagnetic field, a magnetic pole piece including an axial portion thereofsupported within said solenoid cavity exclusive of the use ofnon-magnetic material, and an armature axially translatable relative toand axially and radially magnetically coupled with said magnetic polepiece, while being supported with said magnetic pole piece by a fluidflow restriction that restricts fluid flow with said solenoid cavity andhaving an internal bore therethrough providing fluid communication withsaid solenoid cavity.
 17. The solenoid-actuated valve assembly accordingto claim 16, further including a valve unit, mechanically coupled withsaid armature, and having a fluid cavity coupled in fluid communicationwith a fluid inlet port to which fluid is applied at a first fluidpressure, and a fluid exit port from which said fluid is output at asecond fluid pressure, and containing a valve seat therebetween, whichis adapted to be closed by a valve closing assembly that includes avalve poppet coupled with said moveable magnetic armature, so as toregulate fluid flow between said fluid inlet port and said fluid exitports, and wherein said fluid flow restriction is configured to balancefluid pressures at the fluid inlet and exit ports applied to theopposite sides of said fluid flow restriction, in a manner that iscomplementary to the fluid pressures applied to opposite sides of saidvalve poppet, thereby effectively neutralizing the effects of fluidpressure on poppet position.
 18. The solenoid-actuated valve assemblyaccording to claim 17, wherein said fluid flow restriction comprises agenerally annular-shaped passageway adjacent to said valve closingassembly and extending between said armature cavity and said fluidcavity.
 19. The solenoid-actuated valve assembly according to claim 17,wherein said fluid flow restriction comprises a fluid seal element. 20.The solenoid-actuated valve assembly according to claim 19, wherein saidfluid seal element comprises one of a diaphragm and an O-ring.